net/sched/cls_bpf.c

   1 /*
   2  * Berkeley Packet Filter based traffic classifier
   3  *
   4  * Might be used to classify traffic through flexible, user-defined and
   5  * possibly JIT-ed BPF filters for traffic control as an alternative to
   6  * ematches.
   7  *
   8  * (C) 2013 Daniel Borkmann <dborkman@redhat.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/filter.h>
  19 #include <net/rtnetlink.h>
  20 #include <net/pkt_cls.h>
  21 #include <net/sock.h>
  22
  23 MODULE_LICENSE("GPL");
  24 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
  25 MODULE_DESCRIPTION("TC BPF based classifier");
  26
  27 struct cls_bpf_head {
  28         struct list_head plist;
  29         u32 hgen;
  30 };
  31
  32 struct cls_bpf_prog {
  33         struct sk_filter *filter;
  34         struct sock_filter *bpf_ops;
  35         struct tcf_exts exts;
  36         struct tcf_result res;
  37         struct list_head link;
  38         u32 handle;
  39         u16 bpf_len;
  40 };
  41
  42 static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = {
  43         [TCA_BPF_CLASSID]       = { .type = NLA_U32 },
  44         [TCA_BPF_OPS_LEN]       = { .type = NLA_U16 },
  45         [TCA_BPF_OPS]           = { .type = NLA_BINARY,
  46                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
  47 };
  48
  49 static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
  50                             struct tcf_result *res)
  51 {
  52         struct cls_bpf_head *head = tp->root;
  53         struct cls_bpf_prog *prog;
  54         int ret;
  55
  56         list_for_each_entry(prog, &head->plist, link) {
  57                 int filter_res = SK_RUN_FILTER(prog->filter, skb);
  58
  59                 if (filter_res == 0)
  60                         continue;
  61
  62                 *res = prog->res;
  63                 if (filter_res != -1)
  64                         res->classid = filter_res;
  65
  66                 ret = tcf_exts_exec(skb, &prog->exts, res);
  67                 if (ret < 0)
  68                         continue;
  69
  70                 return ret;
  71         }
  72
  73         return -1;
  74 }
  75
  76 static int cls_bpf_init(struct tcf_proto *tp)
  77 {
  78         struct cls_bpf_head *head;
  79
  80         head = kzalloc(sizeof(*head), GFP_KERNEL);
  81         if (head == NULL)
  82                 return -ENOBUFS;
  83
  84         INIT_LIST_HEAD(&head->plist);
  85         tp->root = head;
  86
  87         return 0;
  88 }
  89
  90 static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog)
  91 {
  92         tcf_unbind_filter(tp, &prog->res);
  93         tcf_exts_destroy(tp, &prog->exts);
  94
  95         sk_unattached_filter_destroy(prog->filter);
  96
  97         kfree(prog->bpf_ops);
  98         kfree(prog);
  99 }
 100
 101 static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
 102 {
 103         struct cls_bpf_head *head = tp->root;
 104         struct cls_bpf_prog *prog, *todel = (struct cls_bpf_prog *) arg;
 105
 106         list_for_each_entry(prog, &head->plist, link) {
 107                 if (prog == todel) {
 108                         tcf_tree_lock(tp);
 109                         list_del(&prog->link);
 110                         tcf_tree_unlock(tp);
 111
 112                         cls_bpf_delete_prog(tp, prog);
 113                         return 0;
 114                 }
 115         }
 116
 117         return -ENOENT;
 118 }
 119
 120 static void cls_bpf_destroy(struct tcf_proto *tp)
 121 {
 122         struct cls_bpf_head *head = tp->root;
 123         struct cls_bpf_prog *prog, *tmp;
 124
 125         list_for_each_entry_safe(prog, tmp, &head->plist, link) {
 126                 list_del(&prog->link);
 127                 cls_bpf_delete_prog(tp, prog);
 128         }
 129
 130         kfree(head);
 131 }
 132
 133 static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle)
 134 {
 135         struct cls_bpf_head *head = tp->root;
 136         struct cls_bpf_prog *prog;
 137         unsigned long ret = 0UL;
 138
 139         if (head == NULL)
 140                 return 0UL;
 141
 142         list_for_each_entry(prog, &head->plist, link) {
 143                 if (prog->handle == handle) {
 144                         ret = (unsigned long) prog;
 145                         break;
 146                 }
 147         }
 148
 149         return ret;
 150 }
 151
 152 static void cls_bpf_put(struct tcf_proto *tp, unsigned long f)
 153 {
 154 }
 155
 156 static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
 157                                    struct cls_bpf_prog *prog,
 158                                    unsigned long base, struct nlattr **tb,
 159                                    struct nlattr *est, bool ovr)
 160 {
 161         struct sock_filter *bpf_ops, *bpf_old;
 162         struct tcf_exts exts;
 163         struct sock_fprog_kern tmp;
 164         struct sk_filter *fp, *fp_old;
 165         u16 bpf_size, bpf_len;
 166         u32 classid;
 167         int ret;
 168
 169         if (!tb[TCA_BPF_OPS_LEN] || !tb[TCA_BPF_OPS] || !tb[TCA_BPF_CLASSID])
 170                 return -EINVAL;
 171
 172         tcf_exts_init(&exts, TCA_BPF_ACT, TCA_BPF_POLICE);
 173         ret = tcf_exts_validate(net, tp, tb, est, &exts, ovr);
 174         if (ret < 0)
 175                 return ret;
 176
 177         classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
 178         bpf_len = nla_get_u16(tb[TCA_BPF_OPS_LEN]);
 179         if (bpf_len > BPF_MAXINSNS || bpf_len == 0) {
 180                 ret = -EINVAL;
 181                 goto errout;
 182         }
 183
 184         bpf_size = bpf_len * sizeof(*bpf_ops);
 185         bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
 186         if (bpf_ops == NULL) {
 187                 ret = -ENOMEM;
 188                 goto errout;
 189         }
 190
 191         memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size);
 192
 193         tmp.len = bpf_len;
 194         tmp.filter = bpf_ops;
 195
 196         ret = sk_unattached_filter_create(&fp, &tmp);
 197         if (ret)
 198                 goto errout_free;
 199
 200         tcf_tree_lock(tp);
 201         fp_old = prog->filter;
 202         bpf_old = prog->bpf_ops;
 203
 204         prog->bpf_len = bpf_len;
 205         prog->bpf_ops = bpf_ops;
 206         prog->filter = fp;
 207         prog->res.classid = classid;
 208         tcf_tree_unlock(tp);
 209
 210         tcf_bind_filter(tp, &prog->res, base);
 211         tcf_exts_change(tp, &prog->exts, &exts);
 212
 213         if (fp_old)
 214                 sk_unattached_filter_destroy(fp_old);
 215         if (bpf_old)
 216                 kfree(bpf_old);
 217
 218         return 0;
 219
 220 errout_free:
 221         kfree(bpf_ops);
 222 errout:
 223         tcf_exts_destroy(tp, &exts);
 224         return ret;
 225 }
 226
 227 static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp,
 228                                    struct cls_bpf_head *head)
 229 {
 230         unsigned int i = 0x80000000;
 231
 232         do {
 233                 if (++head->hgen == 0x7FFFFFFF)
 234                         head->hgen = 1;
 235         } while (--i > 0 && cls_bpf_get(tp, head->hgen));
 236         if (i == 0)
 237                 pr_err("Insufficient number of handles\n");
 238
 239         return i;
 240 }
 241
 242 static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
 243                           struct tcf_proto *tp, unsigned long base,
 244                           u32 handle, struct nlattr **tca,
 245                           unsigned long *arg, bool ovr)
 246 {
 247         struct cls_bpf_head *head = tp->root;
 248         struct cls_bpf_prog *prog = (struct cls_bpf_prog *) *arg;
 249         struct nlattr *tb[TCA_BPF_MAX + 1];
 250         int ret;
 251
 252         if (tca[TCA_OPTIONS] == NULL)
 253                 return -EINVAL;
 254
 255         ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy);
 256         if (ret < 0)
 257                 return ret;
 258
 259         if (prog != NULL) {
 260                 if (handle && prog->handle != handle)
 261                         return -EINVAL;
 262                 return cls_bpf_modify_existing(net, tp, prog, base, tb,
 263                                                tca[TCA_RATE], ovr);
 264         }
 265
 266         prog = kzalloc(sizeof(*prog), GFP_KERNEL);
 267         if (prog == NULL)
 268                 return -ENOBUFS;
 269
 270         tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE);
 271         if (handle == 0)
 272                 prog->handle = cls_bpf_grab_new_handle(tp, head);
 273         else
 274                 prog->handle = handle;
 275         if (prog->handle == 0) {
 276                 ret = -EINVAL;
 277                 goto errout;
 278         }
 279
 280         ret = cls_bpf_modify_existing(net, tp, prog, base, tb, tca[TCA_RATE], ovr);
 281         if (ret < 0)
 282                 goto errout;
 283
 284         tcf_tree_lock(tp);
 285         list_add(&prog->link, &head->plist);
 286         tcf_tree_unlock(tp);
 287
 288         *arg = (unsigned long) prog;
 289
 290         return 0;
 291 errout:
 292         if (*arg == 0UL && prog)
 293                 kfree(prog);
 294
 295         return ret;
 296 }
 297
 298 static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
 299                         struct sk_buff *skb, struct tcmsg *tm)
 300 {
 301         struct cls_bpf_prog *prog = (struct cls_bpf_prog *) fh;
 302         struct nlattr *nest, *nla;
 303
 304         if (prog == NULL)
 305                 return skb->len;
 306
 307         tm->tcm_handle = prog->handle;
 308
 309         nest = nla_nest_start(skb, TCA_OPTIONS);
 310         if (nest == NULL)
 311                 goto nla_put_failure;
 312
 313         if (nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid))
 314                 goto nla_put_failure;
 315         if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_len))
 316                 goto nla_put_failure;
 317
 318         nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_len *
 319                           sizeof(struct sock_filter));
 320         if (nla == NULL)
 321                 goto nla_put_failure;
 322
 323         memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
 324
 325         if (tcf_exts_dump(skb, &prog->exts) < 0)
 326                 goto nla_put_failure;
 327
 328         nla_nest_end(skb, nest);
 329
 330         if (tcf_exts_dump_stats(skb, &prog->exts) < 0)
 331                 goto nla_put_failure;
 332
 333         return skb->len;
 334
 335 nla_put_failure:
 336         nla_nest_cancel(skb, nest);
 337         return -1;
 338 }
 339
 340 static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 341 {
 342         struct cls_bpf_head *head = tp->root;
 343         struct cls_bpf_prog *prog;
 344
 345         list_for_each_entry(prog, &head->plist, link) {
 346                 if (arg->count < arg->skip)
 347                         goto skip;
 348                 if (arg->fn(tp, (unsigned long) prog, arg) < 0) {
 349                         arg->stop = 1;
 350                         break;
 351                 }
 352 skip:
 353                 arg->count++;
 354         }
 355 }
 356
 357 static struct tcf_proto_ops cls_bpf_ops __read_mostly = {
 358         .kind           =       "bpf",
 359         .owner          =       THIS_MODULE,
 360         .classify       =       cls_bpf_classify,
 361         .init           =       cls_bpf_init,
 362         .destroy        =       cls_bpf_destroy,
 363         .get            =       cls_bpf_get,
 364         .put            =       cls_bpf_put,
 365         .change         =       cls_bpf_change,
 366         .delete         =       cls_bpf_delete,
 367         .walk           =       cls_bpf_walk,
 368         .dump           =       cls_bpf_dump,
 369 };
 370
 371 static int __init cls_bpf_init_mod(void)
 372 {
 373         return register_tcf_proto_ops(&cls_bpf_ops);
 374 }
 375
 376 static void __exit cls_bpf_exit_mod(void)
 377 {
 378         unregister_tcf_proto_ops(&cls_bpf_ops);
 379 }
 380
 381 module_init(cls_bpf_init_mod);
 382 module_exit(cls_bpf_exit_mod);